Gene Cloning,Expression and Characterization of Chitinase from Microbulbifer thermotolerans YLW106
To promote value-added utilization of chitin wastes,the chitinase gene was cloned from Microbulb-ifer thermotolerans YLW106 and expressed,and then the enzymatic properties of the recombinant enzyme were characterized.The results showed that the chitinase gene Chi2375 was cloned from M.thermotolerans YLW106,and the recombinant enzyme Chi2375 was expressed in Escherichia coli.Chi2375 showed the opti-mum temperature of 55.0 ℃ and the half-life(t1/2)of 60 h and 2 h at 50 ℃ and 55 ℃,respectively.The opti-mum pH value was 8.0 and the relative activity of the recombinant enzyme Chi2375 remained stably above 85％after incubation at 4 ℃ and pH value 3.5-12.0 for 24 h.In addition,5 mmol • L-1 Cu2+,1％Triton X-100 and 1％DTT improved the activity of Chi2375,with the relative activities of 140％,130％and 180％,respectively.The most suitable substrate was β-chitin.With colloidal chitin as the substrate,the Vmax and Km of Chi2375 were(7.49±0.25)U • mg-1 and(33.75±1.24)mg • mL-1,respectively.The product of the re-action of Chi2375 with colloidal chitosan was chitobiose with the purity above 90％,demonstrating application potential in medicine and food.
Microbulbifer thermotoleranschitinasecloning and expressionpurificationenzymatic properties
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